Process of coloring silver images



Sept., i8, 1934.. R. KAUFHOLD 1,974,334

PROCESS OF-COLORING SILVER IMAGE-.S

Filed sept. 2e, 1932 INVENTOR.'

A TTORNEYS.

Pim@ Sept-.18. 1934 v l- 1,974,334

UNITED STATES. PATENT or-ElcE PROCESS F VCOLORING SILVER 'IMAGES RobertKaufhold, Feldkirch, Austria, assigner to the rm'.Koh-I-Noor-Bleistiftfabrik L. & C. Hardtmuth, (Jeske Budejovice,Czechoslovakia Application September 26, i932, Serial No. 634,981

In German'ynugust 30, 1929 4A claims. (ol. 295-5) 'I'he presentinvention relates to a process of however, besideslight colors alsoblack pigments coloring silver images and particularly to a process ordark colors are applied to the darker areas of of coloring photographicpositives and negatives. the picture, the print is covered with anuncolored Hitherto silver images were colored with transgelatinesolution. The print may now be dried, 1 5 parent colors or coveringdyes. When these but it is also possible tocontinue the treatment 50known coloring processes are used it is', however, with prints in dampstate. 'Iheprintisthereupon not possible to reproduce the. light anddark bleached. Suitable bleaching agents are, for inshades correctly,since the grey silver particles stance, the solutions used by thepreparation of willshine through the layer of colors, wherebyimbromoiland ozobromium prints. Solutions of "'10 pure tones areproduced. Moreover, when Workthis kind will penetrate all layers andconvert the 65 ing after these known methods, it would be neces-.blackened silver of the original image into white sary, in order toobtain satisfactory results, to silver. Simultaneously the ozobromiumcontent color the areas of different light values individof thebleaching agents will cause a hardening of ually and with utmost care.This coloring the pigment layers superimposed on the silver .15 methodis, however, hardly practicable and usuimage in accordance with theimage proper. The 70 ally, therefore, for instance the leaves of clumpsproduct is thereupon washed with tepid water. of trees or bushes aresimply painted green with- During the washing procedure such coloredlayout regard to the fact, that each single leaf comers as still remainsoft will be separated from the prises a plurality of color shades.Therefore, picture. The picture is now treated with a soft evencarefully painted photographic prints will brush and simultaneously thepicture may be re- 75 never be a really artistic reproduction of nature.touched, if desired. Finally the product is flxed The object of thepresent invention is to proand washed in the usual Way. vide a simpleand practical process for producing Instead of painting rthe picturewith pencils colored pictures from photographic prints which orsolutions of pulverulent pigments the dyeing v will give better resultsthan the processes hitherto may be performed by means of colored ortinged, 80

known. regular or irregular crystals or circles, pencils According tothe present invention, in carrying or carbons, bronze colors, shortcolored silk outl a process of the kind referred to` above, the threadsand the like. coloring is performed by applying pigments to a Theessential feature of the present process 3Q photographic negative orpositive, coating the consists in the fact that the original image (the85 pigments with a layer of colored or uncolored finished silver image)iS at first colored with colloid and bleaching and washing the picture.powdered or pencil colors as a single or multi- Through this treatmentthe surplus of pigments colored picture, upon which the colloid, forinand of gelatine is removed. Thereupon the white stance, gelatine andpreferably a dark colored -35 silver image is xed out and the pic.ure iswashed. gelatine, is poured 01' Spread.

' The product obtained is a pure colored picture. The prOCeSS iS ShOWIldagrammatally in the When a photographic positive is to be coloredaccompanying drawing in which Figure 1 indithe process may be carriedout in the following cates the silver image before bleaching; Fig. 2manner: after bleaching and Fig. 3 the completely xed 40` The print ispainted roughly withpowdered pigimage. 95 ments, pencil colors or otherpigment solutions The following takes place: In the process of in whichno couoid is present. Pigment solupouring or spreading, See Fig. 1, thedark liquid tions are not so-called genuine color solutions, as layer ofgelatine moistens the dry powdered color for instance, anilin colorsubstances diluted in lying underneath down to the bottom. There- 4'5water, but insoluble color substances finely divided f01e, by thepenetration 0f the gelatine into the 100 in benzine, turpentine oil,etc., which vclatilize dry red or other powdered Color, a red glue layerafter application, leaving the dry powder color and above it a dark gluelayer lies on the silver behind.v Hereby no regard is taken to light andimagedark tones or shades. Groups of houses are, for In addition to thisis a special characteristic linstance, simply colored brown or yellow,woods 0f the PrOCeSSI The red layer of the powdered 105 and meadowsgreen and the sky blue. The paintcolor forms, as it were, a screen forthe dark ed print is coated with a layer of colloid, preferlayer ofgelatine lying above it. It absorbs the ably of colored or uncoloredgelatine. If the liquid gelatine, but n'ot, the gross coloring parprintis colored only with light pigments, it is ticles contained therein.Therefore, the tone of coated with a dark colored gelatine solution. If,the red glue layer remains pure. 1l(

But it is not always necessary to use a dark coloredfglue layer althoughin most cases such a dark Ycolored-glue layer is applied. nFor cer*-Vtain purposes, another tone may be employed and even a completely plainor colorless layer of glue.

Contrary to other processes in which the initial silver image is broughtinto contact with the already colored layers of colloid, the presentprocess is carried out in a separate manner i. e., at first the pigmentis applied and then the layer of glufe, whereupon both layers areunited.

This is the essential feature of the process. It is Vpresumed that, thefurther treatment is already known.

Thereupon follows the bleaching and tanning of the silver image andtherewith the tanning of the colored layers of gelatine lying above itand the removal of the untanned parts in a bath of Warm water. Thereremains then a colored image of gelatine as shown in Figure 2. Thedelicate graduations are reproduced by light co1- ors, as in the exampleby red, the middle densities by red and a small amount of black, and theshadings by a higher amount of black but in which the red ground shinesthrough.

In this way it isV possible to produce a multicolored image i. e., animage in which the colors appear as in nature. When, for instance in alandscape, the sky is to be reproduced in a blue color, the woods andmeadows in a green color etc., water colors are Vnot suitable for thispurpose. t is true, they already contain the necessary colloid, glue oralbumin, but it is not possible to apply the colorsin a completely equalmanner one with the other. carried out as inthe present process i. e.,when at rst,the coloring is effected by means of pastel colors or withthe pastel crayon and only when the colloid is added, as abovedescribed,

by pouring or spreading it on the layer of colors:Y

Lazur-colors are transparent colors. In Fig. 3 the completely fixedimage is shown.

'I'his is only possible whenY When coloring by means of fatty pigmentsthe process may be performed in a manner now to be described, whereby anengraving-like effect is obtained: YThe fatty pigments are applied tothe picture in the form of dashes or dots, whereupon the silver layerbetween the dashes or dots is bleached and the layer of fattyl matter isremoved by means cf benzene. The picture is thereupon treated in themanner described above.

1. A process of coloring silver images comprising the steps of paintingthe image with suitable pigments, coating it with a layer of colloid,then bleaching it so that the colloid layers on the image becomehardened in accordance with the original image, washing away the solublecolloid and fixing out the bleached silver.

2. A process of coloring silver images-'comprising the ,steps Yoipainting the image with suitable pigments, coating it with a layer ofcolored colloid, then bleaching it so that the colloid layers on theimage become hardened in accordance with the original image, washingaway theY soluble colloid and fixing out the bleached silver. Y i

3. A process of coloring silver images comprising the steps of paintingthe image with suitable pigments, coating it with a layer of anuncolored colloid, then bleaching it'so that the colloid layers on theVimage become hardened in accordance with the original image-washingaway the soluble colloid and fixing out the bleached silver.

' 4. A process of coloring silver images comprising the steps ofpainting the image with a phrrality of layers of suitable pigments,coating it with a layer of-colloid, then bleaching it so thatVVA thecolloid layers on the image become hardened in accordance with theoriginal image, Washing" away VVthe soluble colloid and xing out thebleached silver. Y

' ROBERT KAUFHOLD.

